/*	$NetBSD$	*/

/*-
 * Copyright (c) 2014 The NetBSD Foundation, Inc.
 * All rights reserved.
 *
 * This code is derived from software contributed to The NetBSD Foundation
 * by Taylor R. Campbell.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 *
 * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
 * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
 * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
 * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS
 * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
 * POSSIBILITY OF SUCH DAMAGE.
 */

#ifndef	_SYS_TASK_H_
#define	_SYS_TASK_H_

#include <sys/types.h>
#include <sys/callout.h>
#include <sys/mutex.h>
#include <sys/queue.h>

struct task;
struct taskqueue;
struct taskworker;
struct delayed_task;

typedef void task_fn_t(struct task *);

struct task {
	struct taskworker	*volatile task_worker;
	task_fn_t		*task_fn;
	TAILQ_ENTRY(task)	task_entry;
};

typedef void delayed_task_fn_t(struct delayed_task *);

struct delayed_task {
	struct task		dt_task;
	struct callout		dt_callout;
};

static inline void
task_init(struct task *task, task_fn_t *fn)
{

	task->task_worker = NULL;
	task->task_fn = fn;
}

void	task_destroy(struct task *);

void	task_done(struct task *);

void	task_schedule(struct task *);
bool	task_cancel(struct task *, kmutex_t *);
bool	task_cancel_async(struct task *);

/* Not part of the API -- don't use this outside delayed_task_init.  */
void	delayed_task_timeout(void *);

static inline void
delayed_task_init(struct delayed_task *dt, task_fn_t *fn)
{

	/*
	 * XXX Sketchy function cast from void (*)(struct task *) to
	 * void (*)(struct delayed_task *).  The memory addresses of
	 * the arguments will be the same.  Is this kosher?  If not,
	 * the API can be adapted, but it's nicer this way.
	 */
	task_init(&dt->dt_task, (task_fn_t *)fn);
	callout_init(&dt->dt_callout, CALLOUT_MPSAFE);
	callout_setfunc(&dt->dt_callout, delayed_task_timeout, dt);
}

void	delayed_task_destroy(struct delayed_task *);

bool	delayed_task_timedout(struct delayed_task *);

typedef uint64_t nsec_t;
typedef uint32_t jitter_t;

void	delayed_task_schedule(struct delayed_task *, nsec_t, jitter_t);
bool	delayed_task_reschedule(struct delayed_task *, nsec_t, jitter_t);
bool	delayed_task_cancel(struct delayed_task *, kmutex_t *);
bool	delayed_task_cancel_async(struct delayed_task *);

#define	TASKQUEUE_PERCPU	0x01

/* PRI_NONE task queue, always available.  */
extern struct taskqueue *system_taskqueue;

int	taskqueue_get(struct taskqueue **, pri_t);
void	taskqueue_put(struct taskqueue *);

int	taskqueue_create(struct taskqueue **, const char *, pri_t, int, int);
void	taskqueue_destroy(struct taskqueue *);

void	taskqueue_schedule(struct taskqueue *, struct task *);
void	taskqueue_schedule_delayed(struct taskqueue *, struct delayed_task *,
	    nsec_t, jitter_t);
void	taskqueue_drain(struct taskqueue *);

void	tasks_init(void);

#endif	/* _SYS_TASK_H_ */